TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Biology > Biology. AS and A2. Mainly Unit 1 Old Spec
Heres some biology notes :
Word Definition
- Blood The complex fluid that circulates in blood vessels
- Plasma The fluid component of blood
- Tissue fluid The fluid that surrounds all living cells. Cells gain their food and oxygen, and secrete their carbon dioxide and waste directly into this fluid. Its composition is similar to blood plasma, but without the large proteins.
- Lymph The fluid that flows in lymph vessels. Lymph is formed by the drainage of tissue fluid. Lymph capillaries are more permeable than blood capillaries, so lymph tends to contain more lipids and high molecular weight proteins than plasma.
- Hydrostatic pressure The fluid pressure of the blood, created by the ventricles of the heart.
- Receptors Something that detects a change e.g. chemoreceptors in respiratory centre
- Effectors Something that reverses a change
- Myogenic The muscle contraction originates from within the heart itself.
- Glycogen A branched polymer made from thousands of glucose molecules.
- Alactic No build up of lactic acid
- Anaerobic No oxygen required
- Transpiration Loss of water from the upper surfaces of a plant. Most water is lost through the stomata on the underside of leaves.
- The transpiration stream The continuous flow of water through the plant, from the roots to the leaves. The xylem tissue is mainly responsible for this flow.
- Symplast pathway Through the cytoplasm of cells (10% of water)
- Apoplast pathway Through the cell walls and spaces around cells (90% of water)
- Endodermis A thin membrane surrounding the vascular tissue
- Casparian strip A waterproof layer that lies between the endodermal cells and the vascular bundle, and prevents water and ions from entering the xylem by the apoplast pathway.
- Cohesion-tension hypothesis The mechanism of transpiration which provides the force that pulls water up the plant.
- Source Part of a plant that provides food (e.g the leaves and other green parts, areas of stored foods e.g. tubers)
- Sink Part of a plant that needs food, notably the roots, flowers, fruits and growing points.
- Translocation The movement of materials e.g. sucrose from sources to sinks via the phloem tissue.
- Xerophyte A plant that is adapted to reduce water loss.
- Xylem This tissue consists of many dead hollow xylem vessels that carry water and dissolved mineral ions up the plant to the leaves and other organs.
- Phloem This tissue consists of mainly living cells, which are tubular in shape These cells carry the products of photosynthesis around the plant, from regions that make food to regions that need it.
- Companion cells Provide the energy for active transport in phloem tissue.
